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Ray_pierrewit

Electrovoice Sentry IVB score

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So I was perusing the local Marketplace when I saw a post for a nice clean pair of Electro Voice Sentry IVBs, no price, best offer. I do not need another pair of speakers, let alone another pair of behemoths like the Sentry IVBs but I couldn't help but offer $400CDN (which I was sure was a ridiculous low ball). Wouldn't you know it, the woman wrote back ten minutes later saying that she accepted the offer! It was a 1 1/2 hour drive away and I went to pick them up today.

 

I was actively looking for the SM-120A horn to try with my modified LaScalas, and for this price it's a no brainer.

 

They came from an estate sale and when I asked if he had any other audio gear he pulled out some really nice looking Mitsubishi stuff: DA-P10 preamp, DA-A15 power amp and matching tuner and turntable. All for $250CDN.

 

All that for roughly $515US, not too shabby! Will put the SM-120A with A55G drivers on top of my LaScalas and see where I go from there.

 

No pictures for now, you'll have to take my word for it.

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Borrowed a pair of those from djk in the mid '80s to use for a church conference. The music through them sounded pretty good. That's a very reasonable price for those.

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Do they look like these in a photo plucked from a Google search?  If so, the drive and the money were clearly worth it.

 

AACD6A41-2669-40CA-86A1-1A0279FEBA58.jpeg

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Thinking back and searching some more, it was EV Eliminators we borrowed from djk (rip). He has posted on here somewhere that the originals weren't very good.

 

I believe the Sentry IVs were better. They certainly look nicer. Can't wait to hear what you think of them.

 

They have two twelve inch woofers in them.

 

Sentry IVB EDS.pdf

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So I spent the better part of the evening getting acquainted with the stock Sentrys. Having enjoyed my LaScalas, both modified and stock, for over 12 years I feel well placed to compare the two, though to be fair, the placement of the Sentrys isn't helping the low end as they aren't tucked into the corners. They're about 3' from the back wall and a couple of feet from the sides. I had tried the LaScalas in a similar placement a couple of back so I'll have to count on my auditory memory to compare.

 

Unsurprisingly, both sets are lean in this position and I have no sub-woofers to lend a hand. I've been treated to the QPies tucked into the corners for the past six months and can now fully appreciate the QPie design and execution, full bass horn down to 50hz with room gain. Of course, what bass is there has real chest impact but needs higher volumes to be satisfactory. Which leads me to what has been a real revelation. The LaScalas when driven to these levels are fatiguing to me. Is it the K400, the room, the placement? Who knows. The Sentrys could be dangerous, because the volume seems to get louder and louder without them feeling as aggressive. I hear no distortion on both models at these levels and beyond with my 2A3 SET amp.

 

The SM-120A sectoral horn is, I believe, a real gem. I don't know what to think of the 1823M driver just yet, would like to try the A55Gs to compare the two. The ST 350A sectoral tweeter is likewise very pleasant, good enough extension for my ears. It's the first time I listen to tweeters that are mounted below the midhorn, which I seem to remember @moray james advocating. Would love if he could elaborate here.

 

The Sentry wins inasmuch as the height of the drivers. The bass bin is 41" high, which places the middle of the tweeter at approximately 37 1/2" and the mid horn at 46", corresponding well to my seated position. The LaScalas are currently sitting on the QPies which greatly helped in this regard. At this height, both models excel at imaging. Good coverage is vital for me, because most of my listening during the day is outside of the sweet spot. I need for my music to sound pleasing and balanced everywhere in my studio and both the Sentry and LaScala tick that box. Dynamics and ability to energize the room are also very similar, effortless.

 

These two are alike in many ways, cousins perhaps. Visually, the LaScala will always have a place in my heart. I find it's design and visual volumes to be just perfect, a feat of engineering and a work of art. The Sentry, well I'm still getting used to the look. The SM 120A is a strange horn to look at, sort of like staring at the gaping mouth of a Cobra.

 

Very quick question: is there any danger in using the A55G (12ohm) in lieu of the 1823M (8ohm) with the current crossover? I'll include the schematic I found for the Sentry IVB.

 

Screen Shot 2021-02-21 at 12.10.31 AM.png

Electrovoice.jpg

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you could grind those tweeter mounts off of the mid horns for a nicer visual and I am sure improved performance. Just a thought, carry on and enjoy them maybe closer to the front wall to pick up some extra room gain after all your Q-pies were corner mounted.

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4 hours ago, moray james said:

you could grind those tweeter mounts off of the mid horns for a nicer visual and I am sure improved performance.

 

What is the material from which the horns are made?  Are they metal, resin, or something else?  Are the cobra’s teeth solid?  If you grind them away will there be holes?

 

Thanks for the photos and the detailed analysis.  

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8 hours ago, Ray_pierrewit said:

So I spent the better part of the evening getting acquainted with the stock Sentrys. Having enjoyed my LaScalas, both modified and stock, for over 12 years I feel well placed to compare the two, though to be fair, the placement of the Sentrys isn't helping the low end as they aren't tucked into the corners. They're about 3' from the back wall and a couple of feet from the sides. I had tried the LaScalas in a similar placement a couple of back so I'll have to count on my auditory memory to compare.

 

Unsurprisingly, both sets are lean in this position and I have no sub-woofers to lend a hand. I've been treated to the QPies tucked into the corners for the past six months and can now fully appreciate the QPie design and execution, full bass horn down to 50hz with room gain. Of course, what bass is there has real chest impact but needs higher volumes to be satisfactory. Which leads me to what has been a real revelation. The LaScalas when driven to these levels are fatiguing to me. Is it the K400, the room, the placement? Who knows. The Sentrys could be dangerous, because the volume seems to get louder and louder without them feeling as aggressive. I hear no distortion on both models at these levels and beyond with my 2A3 SET amp.

 

The SM-120A sectoral horn is, I believe, a real gem. I don't know what to think of the 1823M driver just yet, would like to try the A55Gs to compare the two. The ST 350A sectoral tweeter is likewise very pleasant, good enough extension for my ears. It's the first time I listen to tweeters that are mounted below the midhorn, which I seem to remember @moray james advocating. Would love if he could elaborate here.

 

The Sentry wins inasmuch as the height of the drivers. The bass bin is 41" high, which places the middle of the tweeter at approximately 37 1/2" and the mid horn at 46", corresponding well to my seated position. The LaScalas are currently sitting on the QPies which greatly helped in this regard. At this height, both models excel at imaging. Good coverage is vital for me, because most of my listening during the day is outside of the sweet spot. I need for my music to sound pleasing and balanced everywhere in my studio and both the Sentry and LaScala tick that box. Dynamics and ability to energize the room are also very similar, effortless.

 

These two are alike in many ways, cousins perhaps. Visually, the LaScala will always have a place in my heart. I find it's design and visual volumes to be just perfect, a feat of engineering and a work of art. The Sentry, well I'm still getting used to the look. The SM 120A is a strange horn to look at, sort of like staring at the gaping mouth of a Cobra.

 

Very quick question: is there any danger in using the A55G (12ohm) in lieu of the 1823M (8ohm) with the current crossover? I'll include the schematic I found for the Sentry IVB.

 

Screen Shot 2021-02-21 at 12.10.31 AM.png

Electrovoice.jpg

I like your home made cylindrical poly fusers. Did you notice much a difference in sound stage and spatial image after you installed them?

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2 hours ago, DizRotus said:

 

What is the material from which the horns are made?  Are they metal, resin, or something else?  Are the cobra’s teeth solid?  If you grind them away will there be holes?

 

Thanks for the photos and the detailed analysis.  

https://community.klipsch.com/uploads/monthly_10_2013/post-14184-13819281651038.jpg

https://community.klipsch.com/uploads/monthly_10_2013/post-14184-13819281656472.jpg

https://community.klipsch.com/uploads/monthly_10_2013/post-14184-13819281661622.jpg

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Thanks Moray for posting all of that info. I have to say that Electro-voice really provided excellent documentation and measurements for these models! Reading the polar response tells me that these horns are really well designed. They are made of "rigid urethane foam", so I think grinding the cobra's teeth is out of the question.

 

I won't be putting them into the corners for now as the LaScala/Qpies are still there. I'll be moving the LaScalas into my home shortly and will lay the Sentry's bass bins on their sides to maintain the midhorn/tweeter's proper height. What'll be fun is trying the QPies as the bass bins, will be very easy to accomplish as the crossovers are pushpin type connections. I'll be able to A/B the Sentry bin and Qpies with ease.

 

Can anyone chime in regarding using the 16ohm A55Gs in lieu of the 8ohm 1823M in the SM120A horn?

 

From what I gather, I only need two metalized mylar caps to recap each crossover, 2uf / 100v +/- 5%, 30uf / 70v +/- 10%.

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2 hours ago, moray james said:

I like your home made cylindrical poly fusers. Did you notice much a difference in sound stage and spatial image after you installed them?

 

They are made of coroplast, and I installed them before even installing my system. What I can say, without any hesitation as even my kids could hear it, is that it greatly reduced reverb in my room. The walls and ceiling are very rigid 5/8" plywood, built out of SIP panels, so no 2x4 framing. When my studio was finished being built, the reverb was just outrageous. I could hear a clap springing back and forth in the room for what seemed like a few seconds. After having installed the poly diffusors it has essentially vanished. I've got some on all four walls, along with 4" thick rockwool absorbers are strategic locations, following @Chris A advice in his very informative corner horn imaging thread.

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Thinking back and searching some more, it was EV Eliminators we borrowed from djk (rip). He has posted on here somewhere that the originals weren't very good.
 
I believe the Sentry IVs were better. They certainly look nicer. Can't wait to hear what you think of them.
 
They have two twelve inch woofers in them.
 
Sentry IVB EDS.pdf
You knew DJK from the 80s? I would have loved to have met him..

Sent from my SM-G986U using Tapatalk

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In case you are interested, the bass cabinet is the EV TL 5050. If your woofers are original, they should be the EVM12L. Those are easily worth $100 each. Incredibly efficient woofer.

 

I had a pair I got from JWC a long time ago, when he was clearing out some things.

 

The specs on the bass cabinet is not much different than a La Scala, maybe a little lower bass. The LS has it for good looks, though. Here's a set of builder's plans for the EV:

 

 

TL5050 Builders Plans.pdf

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32 minutes ago, Marvel said:

In case you are interested, the bass cabinet is the EV TL 5050. If your woofers are original, they should be the EVM12L. Those are easily worth $100 each. Incredibly efficient woofer.

 

I had a pair I got from JWC a long time ago, when he was clearing out some things.

 

The specs on the bass cabinet is not much different than a La Scala, maybe a little lower bass. The LS has it for good looks, though. Here's a set of builder's plans for the EV:

 

 

TL5050 Builders Plans.pdf 248.09 kB · 0 downloads

 

The woofers are original alnico which appear to have been repaired as there was a service sticker on one of them. By all accounts the original foam on these woofers were prone to rotting completely. Mine are in good condition so I presume the surrounds had been replaced. Here is a photo from the net which are identical to mine.

 

woofers.jpg

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Well, certainly not the EVM12L models. Doesn't matter really, if the ones you have sound good.

 

The older ones I had were like these:

evm12L.jpg

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On 2/21/2021 at 10:52 AM, Ray_pierrewit said:

They are made of coroplast...

I just saw this thread and upon seeing your photo was going to ask the exact same question. I've been looking at building the exact same kind of diffusers as you did with an eye toward something that is lightweight, inexpensive, and stiff yet bendable.  Where did you purchase the coroplast and has it held up well so far [e.g. have they lost their tension/elasticity (for lack of a better word) -- assuming you are using that to hold them in place]?

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18 hours ago, JMON said:

I just saw this thread and upon seeing your photo was going to ask the exact same question. I've been looking at building the exact same kind of diffusers as you did with an eye toward something that is lightweight, inexpensive, and stiff yet bendable.  Where did you purchase the coroplast and has it held up well so far [e.g. have they lost their tension/elasticity (for lack of a better word) -- assuming you are using that to hold them in place]?

 

The coroplast, I believe, is a really great material for this type of diffuser. They've been installed for two years now and are held in place by tension only. I purchased them in 4x8' sheets at the hardware store, though art supply shops and print shops should also have them. They cut easily with an xacto blade and t square. Aluminum j moulding is cheap and easy to install and works a charm.

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On 2/23/2021 at 9:09 AM, Ray_pierrewit said:

 

The woofers are original alnico which appear to have been repaired as there was a service sticker on one of them. By all accounts the original foam on these woofers were prone to rotting completely. Mine are in good condition so I presume the surrounds had been replaced. Here is a photo from the net which are identical to mine.

 

woofers.jpg

just a comment. For the ongoing usefulness of any thread it is best to attach drawings or photos directly to the thread rather than including a link as links very often go dead leaving the thread missing useful information. Many search archives looking for information and it is nice when it is there to find years or decades from now.

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On 2/18/2021 at 3:12 PM, Ray_pierrewit said:

 

 

All that for roughly $515US, not too shabby! Will put the SM-120A with A55G drivers on top of my LaScalas and see where I go from there.

 

No pictures for now, you'll have to take my word for it.

how do they sound like----------just curious

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